North West Region Risks

Five in Washington State (Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams) and Mount Hood in northern Oregon that are long-lived volcanoes, having erupted recurrently for hundreds of thousands of yearsWhat can happen?

With virtual certainty, Cascade volcanoes will erupt again, even within our lifetimes.

Volcanoes provide us with warning signs of reawakening days to months in advance of an eruption, but exact timing and size can only be estimated.

​Our volcanoes are snow-topped cones that erupt explosively, with lots of ash and deadly mud flows

A common scenario is the eruption of volcanic ash, and later melting snow and ice, which can create lahars (volcanic mudflows). Lahars can surge off a restless or erupting volcano and flow down valleys for tens of miles

​Nine Cascade volcanoes have the potential to erupt in our lifetimes, Moran said. (In Washington they are: Mount Rainier, Mount St. Helens, Glacier Peak, Mount Baker and Mount Adams. In Oregon: Crater Lake, Mount Hood, Newberry Volcano and the Three Sisters.)All are currently quiet, but the eruption that blew off Mount St. Helens’ top in 1980 and the dome-building eruptions that followed in 2004-2008 show how quickly the giants can stir to life.

The most likely scenario, though, is that any eruption will be preceded by days to weeks of seismic rumblings, ground movement and gas emissions that signal the movement of magma — and which can be detected by ongoing monitoring at all the region’s volcanoes.